Chondrostereum purpureum as a biological control agent in forest vegetation management. I. Efficacy on speckled alder, red maple, and aspen in eastern Canada

As part of a national initiative, a series of experiments were established to evaluate the field efficacy of the indigenous fungus Chondrostererum pur pureum (Pers. ex Fr.) Pouzar as a biological agent in woody vegetation cont rol. Separate experiments involving manual cuttings of speckled alder (Alnu s rugosa (Du Roi) Spreng.), red maple (Acer rubrum L.), and aspen (Populus tremuloides Michx.) employed a common suite of treatments and randomized co mplete block design with five replications. Treatments, applied between Jun e 26 and 29, 1995, included two formulations, each combined with two fungus isolates, 2139 from British Columbia and JAM6 from Ontario. Cutting only ( no treatment) and stump treatments with triclopyr (Release(R)) and blank fo rmulations were used as controls. Two growing seasons after treatment, tric lopyr provided significantly greater control of target species than C. purp ureum. The fungus exhibited its greatest efficacy on alder, resulting in a 72% reduction in stem volume index and 19% clump mortality over untreated c ontrols. On red maple, isolate 2139 provided a 32% reduction in the volume of stump sprouts. On aspen, both isolates of C. purpureum resulted in a 35% reduction in the volume of stump sprouts and isolate 2139 provided an 88% reduction in the volume of root suckers. Efficacy appeared to vary among fu ngus isolates and target species, while formulation was less important.